Calculating Tire Revolutions and Angular Speed in a Braking Car

[balling12]

Homework Statement

A car initially traveling at 25.9 m/s undergoes a constant negative acceleration of magnitude 2.10 m/s2 after its brakes are applied.
(a) How many revolutions does each tire make before the car comes to a stop, assuming the car does not skid and the tires have radii of 0.330 m? ... revs
(b) What is the angular speed of the wheels when the car has traveled half the total distance? .. rad/s

Homework Equations

The Attempt at a Solution

I used the kinematic equation to find the time it takes to come to a stop: 12.3 secs and the distance traveled: 305.67 m. I am unsure how to find the number of revolutions the tires make. However i worked out part B using the equation: W final^2=W initial^2+ 2(alpha)(Change in theta) and got the answer 19.1 rads but it is wrong.

 

[Doc Al]

I used the kinematic equation to find the time it takes to come to a stop: 12.3 secs and the distance traveled: 305.67 m.

Redo that last calculation. Hint: What's the average speed of the car as it comes to rest?

I am unsure how to find the number of revolutions the tires make.

Hint: What's the circumference of the tires?

 

[balling12]

Redo that last calculation. Hint: What's the average speed of the car as it comes to rest?
im not sure?

Hint: What's the circumference of the tires?

Circumference is pie x diameter right?

 

[Doc Al]

Circumference is pie x diameter right?

Yes.